1. Field of the Invention
The present invention relates to a head-up sight usable as a gunsight, and enabling landscape to be observed simultaneously with a collimated image of a reticle.
2. Description of the Prior Art
Such sights include a reticle generator which may itself include a cathode ray tube (CRT) for example, an optical collimator device comprising one or more lenses, and a partially reflective plate having parallel faces. The plate serves to reflect the collimated image of the reticle towards the eye while enabling an external landscape to be obeserved at the same time. In such equipment, the reticle generator and the collimating optics are mounted in the same housing. If the housing is located in the field of view of the observer using the sight, it may constitute a considerable mask by virtue of its size. In such circumstances, the observer's eye sees clearly those images which are transmitted through the partially reflective plate, but does not see other portions of the landscape which are hidden by the obstacle of the housing for the optical collimator device.
Furthermore, in order to change the direction of aim, the reticle is caused to move over the CRT screen. The limits of reticle movement on the screen determine the size of field for the collimating optics, and this field is large relative to the size of the reticle. An optical collimator device capable of such performance is not simple.
Preferred embodiments of the present invention provide a head-up sight which does not mask the field of view in the manner described above, which makes use of easily fabricated optical components, and which has a wide field of aim.